I'm needing to remove several hundred 2 x 2 vertically installed "pickets" from a deck railing but they're affixed along the top and bottom horizontal boards of the railing with 2 1/2" wood screws, with two screws in the top and two screws in the bottom (so four screws per picket). These phillips head woodscrews have been painted over many many times so the slots are filled with paint so can't get the driver bit in without digging out the old paint with an awl, and even then most of these old screws (most rusted to various extents) are quite stubborn and want to strip before giving/turning for me. I tried using an easy out (and even that didn't work so hot) on a few but needing to pre-drill a hole into every screw head for the easy out for all these screws would take forever, plus it would wear out the drill bit. I'd like to remove the pickets without destroying them. Any comments/suggestions for getting these blasted screws out unscrewed appreciated.

I tried searching the Internet for answers and just became more confused. Specifically I would like to know when or how the different types of lock washers are used and the advantages or disadvantages of each type. The types are the common split "spring" lock washer, the internal star lock washer, the external star lock washer and the Belleville washer. For the first three I have read that none of them have any advantage over a properly torqued nut/bolt assembly but if that is true then why use them at all? Star washers are obviously more expensive and if they provide no more benefits than a split washer then why use them? Belliville washers are a breed apart and I can't say I have ever seen them used except on electrical connections.